New3d image viewer

A simple slice viewer of 3D images which also allows to display thresholded set of points.
Needs PR #620 of DGtal 
![capture decran 2013-05-21 a 21 47 50](https://f.cloud.github.com/assets/772865/544442/886b2366-c24f-11e2-8357-3a3aa040af6b.png)